Magnetoresistance of Mg, Cu, Sb, and Al at Liquid Helium Temperatures

The resistance of pure samples of magnesium, copper, antimony, and aluminum was measured at temperatures between 1.1^∘{}K and 4.22^∘{}K in transverse magnetic fields ranging from zero to 22 kg. In a magnesium specimen the dependence of the magnetoresistance on the resistance in zero field was in strict agreement with the Kohler rule, even though the temperature coefficient of the resistance in zero field was negative. The copper samples also showed negative temperature coefficient of resistance, and the temperature dependence of the magnetoresistance was qualitatively in accord with the Kohler rule. The second derivative with respect to temperature of the resistance of the copper samples in zero field was negative in the liquid helium range.